The present invention relates to an electrophotographic photoreceptor and a production method of the same, as well as a process cartridge and an image forming apparatus in which said photoreceptor is installed.
In recent years, as electrophotographic photoreceptors, those which comprise organic photoconductive materials have been widely employed. The organic photoreceptors exhibit more advantageous features than other photoreceptors in such a manner that the materials corresponding to various exposure light sources ranging from visible light to infrared light tend to be developed, materials which do not result in environmental pollution can be chosen, and the production cost is relatively low. The only disadvantage is that the mechanical strength is not sufficiently high, and during copying or printing of a number of sheets, the surface of the photoreceptor results in wear and abrasion.
The surface of electrophotographic photoreceptors is subjected to direct application of electrical and mechanical external forces from a charging unit, a development unit, a transfer means, a cleaning unit, and the like. Therefore, durability is required to counter these external forces. Specifically, sufficient durability is required to counter the generation of wear and abrasion due to sliding friction on the photoreceptor surface, and degradation of the photoreceptor surface due to ozone and active oxygen generated during corona discharge.
In order to satisfy the various properties mentioned above which are required for the photoreceptor surface, various factors have been investigated. Namely, it is reported that by employing BPZ polycarbonate as a binder (a binding resin) on the photoreceptor surface, surface wear properties as well as toner filming properties are enhanced. Furthermore, Japanese Patent Publication Open to Public Inspection No. 6-118681 discloses a hardenable silicone resin containing colloidal silica, which is employed as a photoreceptor surface protecting layer.
However, the photoreceptor in which the BPZ polycarbonate binder is employed exhibits insufficient wear resistant properties and exhibits insufficient durability. On the other hand, the surface layer comprised of the hardenable silicone resin containing colloidal silica exhibits improved wear resistant properties, however, during repeated use, electrophotographic properties are insufficient and tend to result in background staining, as well as image blurring and sufficient durability is not achieved.
As a method to solve such problems, Japanese Patent Publication Open to Public Inspection Nos. 9-124943 and 9-190004 propose photoreceptors, having as a surface layer, the layer of a resin prepared by bonding an organic silicone-modified positive hole transportable compound to hardenable organic silicone based high polymer molecules. However, this resin layer results in background staining as well as image blurring at high humidity, and also exhibits insufficient durability.